1. Field of the Invention
This invention relates to an articulated tube for use in an endoscope or the like, and more particularly to an articulated tube structure arranged between the head and the flexible tube of an endoscope or the like for permitting the head to be tilted by selective manipulation of pull wires extending through the articulated tube structure and the flexible tube.
2. Description of the Prior Art
The endoscope or the like used for inspection or diagnosis of human body cavities like stomach, intestines and so forth has a long flexible tube to be inserted into the human body or the like. The flexible tube has a head at its end via an articulated tube structure. The articulated tube is bendable to direct the head in a desired direction by manipulation of pull wires extending through the articulated tube and the flexible tube.
In the endoscope, the flexible tube should be long enough to insert the head into deep portions of the body to enhance the performance of the endoscope. Therefore, the endoscope has these days a very long flexible tube. As the length of the flexible tube increases, the friction between the pull wires and the flexible tube increases and the manipulation of the pull wires becomes difficult. Particularly, as the length of the flexible tube increases, the number of bent portions of the flexible tube increases and the friction further increases. As the friction increases, the angle at which the articulated tube is bendable is reduced. With the small angle at which the articulated tube is bendable, it is difficult for the endoscope to be inserted in a complicated cavity. Further, it becomes difficult to inspect deep portions in the cavities. In addition, since an endoscope which cannot be bent at a large angle causes great pain to the human body, it becomes difficult to conduct observation, inspection, diagnosis or medical treatment for a long period of time.